The mother and boy were able to get into a lifeboat, and they were rescued by a merchant ship that responded to the yacht’s distress calls, AP said. But the girl and her father swam for hours in 33-foot waves in the cold water before they were rescued by the Portuguese navy.

The little girl died of hypothermia after being pulled from the ocean waters, the news agency said.

The severe weather resulted in four yachts sending distress signals, the navy said in a press release. During a 24-hour time period, 12 people were rescued from those yachts.